That’s a good point. The show really did have fantastic props. IMO, the rifle didn’t quite fit the design aesthetic that evolved after the pilots, but it’s beautifully made. The last reasonably well vetted images of the rifle that were released show it in nice condition. No odd paint blobs…
Yes, of course the show’s aesthetic was still in flux during the pilots, and also for a while after (I’d argue that the look of the show, both in terms of sets/props and cinematography/lighting really started to gel around “The Naked Time” or so). It would seem that the rifle was abandoned in favor of the also-abandoned “phaser 3”, with extra parts to be added to the phaser 2 to turn it into a rifle.